This is the CodeSystem that contains all the codes in ISO 639-2: Codes for the representation of names of languages -- Part 2: Alpha-3 code (http://terminology.hl7.org/CodeSystem/iso639-2) and ISO 639-2: Codes for the representation of names of languages -- Part 2: Alpha-3 code (http://terminology.hl7.org/CodeSystem/iso639-2). E.g. what you have to deal with if you get resources containing codes in either of them